The dangerous-goods class for hazards that don’t fit classes 1–8: lithium batteries, dry ice, magnetized material, environmentally hazardous substances, elevated-temperature materials, and vehicles or engines with batteries or fuel. Because it’s the catch-all, Class 9 is where a huge share of modern freight lands — most of all lithium batteries, which is why so many "ordinary" electronics and equipment shipments are regulated.
Full guideWhat is Class 9, and why so much freight ends up in it →